This invention relates to a method of improving the flavor and aroma of previously conventionally dried undesirable green coffee beans before roasting and, more particularly, to a method of improving the flavor and aroma of previously conventionally dried undesirable green coffee beans before roasting to overcome any significant reduction in their flavor and aroma, and thus unevenness in their quality, that may be caused by varying condition which they are subjected to prior to roasting.
Green coffee beans that are dried in a conventional manner subsequent to harvesting and have desirable flavor and aroma are subsequently influenced by the ambient temperature, humidity, and ventilation available during the period of storage and/or shipment prior to roasting. The characteristics of green coffee beans, especially those which give coffee its splendid aroma and flavor, become very uneven, under adverse storage conditions when the beans are of a single species and harvested at the same time of the year. It is very difficult to satisfactorily roast and then derive a brewed coffee of consistently good flavor and aroma from such undesirable green coffee beans since the undesirable characteristics of green coffee beans subjected to adverse storage conditions are carried forward into the brewed coffee. It is known that it is not a completely satisfactory solution to those problems to merely store green coffee beans in an environment in which an appropriate temperature, humidity and an adequate ventilation are maintained to render the beans desirable for roasting.
Various attempts have been made to solve this problem by changing the conditions of the roasting process, but none of them have been very successful.
U.S. Pat. No. 1,972,184 to Closmann et al. is understood to teach an improvement in the double roasting method wherein coffee beans are first preroasted for a duration of about 20 to 50% of the time usually necessary for a normal roasting process and then treated by steam to remove injurious substances. The double roasting method is used to drive out the undesirable flavor by virtue of coffee beans being preroasted at a predetermined degree and then removed from the roaster. The patent is understood to teach another method on which green coffee beans are treated by steam just before roasting. It has been determined that these methods are sometimes successful in deriving good flavor but that it is difficult to predictably and consistently provide a uniform flavor in accordance with the teachings of the Closmann et al. patent.
U.S. Pat. No. 1,499,780 to Oprean, which teaches methods somewhat similar to the methods of the Closmann et al. patent, relates to an improvement in the double roasting method wherein cold water is sprayed over the coffee beans in the roasting process to remove undesirable substances. U.S. Pat. No. 3,345,180 to Smith is understood to teach a method in which pressure is controlled in the roasting and cooling process to select the constituents to be removed. U.S. Pat. No. 2,343,228 to Sperti is understood to teach a method in which coffee beans are heated under reduced pressure during the first portion of a roasting process. However, the coffee beans treated by the process of Sperti are no longer green beans. U.S. Pat. No. 1,640,648 to Cross is understood to teach a method in which coffee beans are treated with alkaline substances to decaffeinize the coffee, which method is quite different from that disclosed in the present invention.
Sivetz et al. in Volume 1 of the treatis Coffee Processing Technology, the AVI Publishing Company, Inc. 1963, in Chapter 5 entitled "Machine Drying of Coffee", deals with the drying of freshly harvested coffee beans. In this regard, particularly at Pages 116, 117, and 121 through 123, various general principles of machine drying, the optimum drying conditions, and the drying capacity of air used in such procedures are discussed. However, as is recognized in the art, freshly harvested coffee beans such as those conventionally dried by the teachings of Sivetz et al. are sometimes subjected to a fermentation process or more commonly stored for long periods of time under adverse conditions. Frequently the most adverse storage conditions are encountered in shipment of the dried coffee beans from the region where they are grown and dried to a distant market where the dried beans are further processed and roasted. Thus, while unprocessed dried coffee beans are technically "green" coffee beans there is in fact a vast difference between the characteristics of green coffee beans just subsequent to the processing as by the teachings of Sivetz et al. and green coffee beans processed by the teachings of Sivetz et al. and subsequently subjected to adverse strong conditions prior to roasting.
The following table shows a comparison of the characteristics of the coffee brewed from previously conventionally dried undesirable green coffee beans treated before roasting by the process of this invention, by the process of Sivetz et al. and by the combined process of Sivetz et al. and Closmann et al., which comprise the results of comparative tests and organoleptic assessment.
__________________________________________________________________________ Process of Combined Sivetz Process of this Process of et al. & Closmann Characteristics Invention Sivetz et al. et al. Processes __________________________________________________________________________ Taste and Smell Rich natural Poor natural Poor natural flavor and flavor and no flavor and no excellent relish. relish. relish. To the Tongue Soft and Rough and Intermediate. Pleasant. Unpleasant. Storability of Slightly Better than Good. roasted beans inferior. convention- and ground beans ally treated beans. Other charac- Most suitable Suitable for brewing coffee teristics for brewing over a longer time in a (relative to coffee in a relatively large quantity for brewing) small quantity in commercial purposes. a short time at home or elsewhere. __________________________________________________________________________
In summary, the process of Sivetz et al. is concerned merely with the removal of some undesirable substances from freshly harvested coffee beans. The processes of Sivetz et al. and the steam distillation of Closmann et al., when combined merely provide a process for double removal of undesirable substances without any step for developing a new and desirable flavor.
Green coffee beans desirable or suitable for roasting may be defined as those which can impart to the coffee brewed from roasted beans a good fragrance, a splendid taste, a pleasing smell or aroma and a quality of being soft and pleasant to the tongue. Visual inspection of green beans does not generally permit evaluation of the beans with respect to those qualities. But people experienced in the art of coffee production can generally judge the quality of dried green beans by the aroma. Desirable green coffee beans have a strong desirable smell of fermentation, while bad beans have a poor flavor or give out an offensive smell. It is well known in the art of coffee roasting that brewed coffee which is excellent in both taste and smell or aroma can be derived from roasting green beans having a strong desirable smell, while green beans having a weak or poor smell or aroma make only brewed coffee which is inferior in both taste and smell.
It has been recognized as necessary to subject undesirable green coffee beans to some special treatment before roasting to avoid the unevenness in the quality thereof as far as possible, while developing the flavor or aromatic qualities inherent in green coffee beans, and some effective method of such treatment has long been awaited.